Method and system for utilizing undersampling to remove in-band blocker signals

ABSTRACT

Methods and systems for wireless communication are disclosed and may include band-limiting a wireless signal utilizing a programmable bandpass filter, generating a first signal by undersampling utilizing a clock signal and generating a second signal by undersampling the signal utilizing a delayed version of the clock signal, which may then be subtracted from the first signal. The filter may comprise a microstrip or a coplanar waveguide bandpass filter. The delay may be variable, and may be defined as an inverse of a frequency difference between the desired channel and a blocker signal. The bandwidth of the filter may be centered at the desired channel. The clock signal may be generated at a frequency which may be an integer sub-harmonic of the desired channel, and may be greater than twice a bandwidth of the filter. The delay may be controlled by a programmable delay circuit, which may comprise CMOS inverters.

CROSS-REFERENCE TO RELATED APPLICATIONS/INCORPORATION BY REFERENCE

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FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

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FIELD OF THE INVENTION

Certain embodiments of the invention relate to wireless communication.More specifically, certain embodiments of the invention relate to amethod and system for utilizing undersampling to remove in-band blockersignals.

BACKGROUND OF THE INVENTION

In 2001, the Federal Communications Commission (FCC) designated a largecontiguous block of 7 GHz bandwidth for communications in the 57 GHz to64 GHz spectrum. This frequency band may be used by the spectrum userson an unlicensed basis, that is, the spectrum is accessible to anyone,subject to certain basic, technical restrictions such as maximumtransmission power and certain coexistence mechanisms. Thecommunications taking place in this band are often referred to as ‘60GHz communications’. With respect to the accessibility of this part ofthe spectrum, 60 GHz communications is similar to other forms ofunlicensed spectrum use, for example Wireless LANs or Bluetooth in the2.4 GHz ISM bands. However, communications at 60 GHz may besignificantly different in aspects other than accessibility. Forexample, 60 GHz signals may provide markedly different communicationschannel and propagation characteristics, not least due to the fact that60 GHz radiation is partly absorbed by oxygen in the air, leading tohigher attenuation with distance. On the other hand, since a very largebandwidth of 7 GHz is available, very high data rates may be achieved.Among the applications for 60 GHz communications are wireless personalarea networks, wireless high-definition television signal, for examplefrom a set top box to a display, or Point-to-Point links.

Further limitations and disadvantages of conventional and traditionalapproaches will become apparent to one of skill in the art, throughcomparison of such systems with the present invention as set forth inthe remainder of the present application with reference to the drawings.

BRIEF SUMMARY OF THE INVENTION

A system and/or method for utilizing undersampling to remove in-bandblocker signals, substantially as shown in and/or described inconnection with at least one of the figures, as set forth morecompletely in the claims.

Various advantages, aspects and novel features of the present invention,as well as details of an illustrated embodiment thereof, will be morefully understood from the following description and drawings.

BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is a diagram illustrating an exemplary wireless communicationsystem, in accordance with an embodiment of the invention.

FIG. 2 is a block diagram illustrating a blocker signal filteringsystem, in accordance with an embodiment of the invention.

FIG. 3A is a block diagram illustrating a cross sectional view of amicrostrip bandpass filter, in accordance with an embodiment of theinvention.

FIG. 3B is a block diagram of an exemplary microstrip bandpass filter,in accordance with an embodiment of the invention.

FIG. 3C is a block diagram illustrating a cross sectional view of acoplanar waveguide bandpass filter, in accordance with an embodiment ofthe invention.

FIG. 3D is a block diagram of an exemplary coplanar waveguide bandpassfilter, in accordance with an embodiment of the invention.

FIG. 4 is a block diagram illustrating a desired RF signal and a blockersignal, in accordance with an embodiment of the invention.

FIG. 5 is a flow diagram illustrating a dual-undersampling blockersignal cancellation process, in accordance with an embodiment of theinvention.

DETAILED DESCRIPTION OF THE INVENTION

Certain aspects of the invention may be found in a method and system forutilizing undersampling to remove in-band blocker signals. Exemplaryaspects of the invention may comprise band-limiting a received wirelesssignal utilizing a programmable bandpass filter, generating a firstsignal by undersampling the signal utilizing a clock signal andgenerating a second signal by undersampling the signal utilizing theclock signal with an added time delay, which may then be subtracted fromthe first signal. The programmable bandpass filter may comprise amicrostrip or a coplanar waveguide bandpass filter. The added time delaymay be variable, and may be defined as an inverse of a differencebetween the desired channel and a blocker signal. The bandwidth of theprogrammable bandpass filter may be centered at the desired channel. Theclock signal may be generated at a frequency which may be an integersub-harmonic of the desired channel, and may be greater than twice abandwidth of the programmable bandpass filter. The time delay may becontrolled by a programmable delay circuit, which may comprise CMOSinverters.

FIG. 1 is a diagram illustrating an exemplary wireless communicationsystem, in accordance with an embodiment of the invention. Referring toFIG. 1, there is shown an access point 112 b, a computer 110 a, aheadset 114 a, a router 130, the Internet 132 and a web server 134. Thecomputer or host device 110 a may comprise a wireless radio 111 a, ashort-range radio 111 b, a host processor 111 c, a host memory 111 d anda processor 111 e. There is also shown a wireless connection between thewireless radio 111 a and the access point 112 b, and a short-rangewireless connection between the short-range radio 111 b and the headset114 a.

Frequently, computing and communication devices may comprise hardwareand software to communicate using multiple wireless communicationstandards. The wireless radio 111 a may be compliant with a mobilecommunications standard, for example. There may be instances when thewireless radio 111 a and the short-range radio 111 b may be activeconcurrently. For example, it may be desirable for a user of thecomputer or host device 110 a to access the Internet 132 in order toconsume streaming content from the Web server 134. Accordingly, the usermay establish a wireless connection between the computer 110 a and theaccess point 112 b. Once this connection is established, the streamingcontent from the Web server 134 may be received via the router 130, theaccess point 112 b, and the wireless connection, and consumed by thecomputer or host device 110 a. The processor 111 e may control signalprocessing, clock signals and delays, for example, in the short rangeradio 111 b.

It may be further desirable for the user of the computer 110 a to listento an audio portion of the streaming content on the headset 114 a.Accordingly, the user of the computer 110 a may establish a short-rangewireless connection with the headset 114 a. Once the short-rangewireless connection is established, and with suitable configurations onthe computer enabled, the audio portion of the streaming content may beconsumed by the headset 114 a. In instances where such advancedcommunication systems are integrated or located within the host device110 a, the radio frequency (RF) generation may support fast-switching toenable support of multiple communication standards and/or advancedwideband systems like, for example, Ultrawideband (UWB) radio. Otherapplications of short-range communications may be wirelessHigh-Definition TV (W-HDTV), from a set top box to a video display, forexample. W-HDTV may require high data rates that may be achieved withlarge bandwidth communication technologies, for example UWB and/or60-GHz communications.

Undersampling may be utilized to remove blocker signals in 60 GHzwireless systems. If the clock signal for an undersampling process isconfigured to be an integer sub-harmonic frequency of the desired signalfrequency and the clock signal for a second undersampling process is atthe same frequency but delayed by a variable time, the reduction and/orelimination of a blocker signal may be optimized. The clock signals anddelay time may be controlled by a processor, such as the processor 111e.

FIG. 2 is a block diagram illustrating a blocker signal filteringsystem, in accordance with an embodiment of the invention. Referring toFIG. 2, there is shown a low noise amplifier (LNA) 201, a band passfilter (BPF) 203, sample and hold circuits (S/H) 205A and 205B, an adder211 and a programmable delay circuit 213. The S/H circuit 205A maycomprise a capacitor 207A and switches 209A and 209B, and the S/Hcircuit 205B may comprise a capacitor 207B and switches 209C and 209D.

The LNA 201 may comprise suitable circuitry, logic and/or code that mayenable the amplification of a received signal. The gain level of the LNA201 may be adjustable, depending on the magnitude of the received signaland the desired signal level at the output of the LNA 201. The input ofthe LNA 201 may be enabled to receive an RF signal at a desiredfrequency. The output of the LNA 201 may be communicatively coupled tothe BPF 203.

The BPF 203 may comprise suitable circuitry, logic and/or code that mayenable band-limiting a received signal by only allowing a signal withina particular frequency band to pass. The BPF 203 may comprise aprogrammable microstrip (MS) or coplanar waveguide (CPW) filter, suchthat the allowed frequency band may be adjustable. The microstrip orcoplanar waveguide filter designs may comprise conductive paths in adielectric material to create a variable inductance and capacitancestructure that may be utilized to create a bandpass filter. By changingthe dimensions, spacing and/or arrangement of microstrip or coplanarwaveguide sections within the bandpass filter, the center frequency andbandwidth may be adjusted. This may be described further with respect toFIG. 3

The S/H circuit 205A and S/H circuit 205B may comprise suitablecircuitry, logic and/or code that may enable sampling a received signalat a desired sampling frequency, as indicated by the input clock signal213, f_(CLK), or delayed clock signal 217, f_(CLK+Td), in FIG. 2. Theswitches 209A/209B and 209C/209D may open and close at the samplingfrequency f_(CLK) to couple the input signal received from the BPF 203.The capacitors 207A and 207B may enable storage of charge to hold thesampled voltage before communicating it to the adder 211. The S/Hcircuit 205A may be enabled to sample a received input voltage at asampling frequency of f_(CLK) as indicated in FIG. 2. Similarly, the S/Hcircuit 205B may be enabled to sample the same received input voltage ata sampling frequency of f_(CLK), but with a time delay, T_(d), asindicated by the delayed clock signal 217.

The adder 211 may comprise suitable circuitry, logic and/or code thatmay enable summing signals received at its inputs. In instances where asignal may be communicated to a negative terminal of the adder 211, thatsignal may be subtracted from a signal communicated to a positiveterminal. In this manner, the output signal of the adder 211 maycomprise the output of the S/H circuit 205A minus the output of the S/Hcircuit 205B.

The programmable delay circuit 213 may comprise suitable circuitry,logic and/or code that may enable delaying a clock signal beforecommunicating it to the S/H circuit 205B. The programmable delay circuit213 may be enabled to tune the delay time of the clock signal 215 togenerate the delayed clock signal 217 for the S/H circuit 205B by addinga variable amount of delay to the signal. The programmable delay circuit213 may comprise CMOS inverter circuits, for example.

In operation, an input RF signal may be communicated to the LNA 201,which may amplify the signal with a desired gain level. The amplifiedsignal may then be communicatively coupled to the BFP 203. The BPF 203may filter out signals at frequencies except for those within thedesired bandwidth. The filtered signal may then be communicated to theS/H circuit 205A and the S/H circuit 205B for undersampling.

Sampling theory may require that to prevent aliasing, a signal may besampled at twice the frequency of the signal. Accordingly, if a widebandsignal may first be bandpass filtered to only the frequency range ofinterest, then a lower sampling frequency, or twice the bandpass filterbandwidth, may be utilized. In this regard, a microstrip or coplanarwaveguide filter may enable receiving signals up to extremely highfrequencies. Accordingly the programmable microstrip or coplanarwaveguide filter may be centered around a desired RF frequency and thefiltered signal may be sampled at a frequency twice the bandwidth of thefilter rather than at twice the frequency of the received RF signal. Forexample, a received signal may comprise a 60 GHz carrier modulated by asignal with baseband bandwidth of less than 5 Ghz. In this manner, themicrostrip filter may be controlled to be centered at 60 Ghz with abandwidth of 5 GHz and the resulting signal may be sampled at 10 GHz,rather than the 120 GHz sampling rate required by signal theory for thereceived RF signal without band-limiting.

In instances where a blocking signal may be present, such as from aninterference source, the S/H circuit 205B may be utilized to remove theblocker signal. The frequency offset Δf, or frequency difference betweenthe desired channel and the blocker signal may be utilized to adjust thetime delay, T_(d), for the delayed clocking signal 217 for the S/Hcircuit 205B. T_(d) may be defined as the inverse of Δf, and may begenerated by the programmable delay circuit 213 comprising CMOS buffersor inverters, for example. The frequency offset, Δf, may be negative forblocker signals with a frequency less than the signal frequency, andpositive for blocker signal frequencies greater than the signalfrequency.

Subtracting the second undersampled signal 219, generated by the S/Hcircuit 205B, from the first undersampled signal 221, generated by theS/H circuit 205A at the adder 211, may result in the desired signal withthe blocker signal removed at the output of the adder 211.

FIG. 3A is a block diagram illustrating a cross-sectional view of amicrostrip bandpass filter, in accordance with an embodiment of theinvention. Referring to FIG. 3A, there is shown a microstrip bandpassfilter (MS-BPF) 320. The MS-BPF 320 may comprise a passivation layer301, a signal conductive line 303, a ground plane 305, an oxide layer307 and a substrate 309.

The passivation layer 301 may comprise an oxide, nitride or otherinsulating layer that may provide electrical isolation between thesignal conductive line 303, the ground plane 305 and other circuitry onthe substrate 309. The passivation layer 301 may provide protection fromenvironmental factors for the underlying layers of the MS-BPF 320. Inaddition, the passivation layer 301 may be selected based on itsdielectric constant and its effect on the electric field that may bepresent between conductive lines.

The signal conductive line 303 may comprise metal traces embedded in theoxide layer 307. In another embodiment of the invention, the signalconductive line 303 may comprise poly-silicon or other conductivematerial. The separation and the voltage potential between the signalconductive line 303 and the ground plane 305 may determine the electricfield generated therein. In addition, the dielectric constant of theoxide 307 may also determine the electric field between the signalconductive line 303 and the ground plane 305.

The oxide layer 307 may comprise SiO₂ or other oxide material that mayprovide a high resistance insulating layer between the signal conductiveline 303 and the ground plane 305. In addition, the oxide layer 307 mayprovide a means for configuring the electric field between the signalconductive line 303 and the ground plane 305 by the selection of anoxide material with an appropriate dielectric constant.

The substrate 309 may comprise a semiconductor or insulator materialthat may provide mechanical support for the MS-BPF 320 and other devicesthat may be integrated. The substrate 309 may comprise Si, GaAs,sapphire, InP, GaO, ZnO, CdTe, CdZnTe and/or Al₂O₃, for example, or anyother substrate material that may be suitable for integrating coplanarwaveguide structures.

In operation, an AC signal may be applied across the signal conductiveline 303 and the ground plane 305. The spacing between the conductiveline 303 and the ground plane 305, as well as the pattern of theconductive lines, may generate an inductance and a capacitance that maybe utilized for filtering purposes, specifically bandpass filtering, inthe present invention. In addition, programmable impedances may becoupled across the microstrip devices in the MS-BFP 320 to tune thecenter frequency and bandwidth and will be described further withrespect to FIG. 3B. The MS-BPF 320 may enable the undersampling ofreceived signals at a much lower sampling frequency than withoutfiltering. Two undersampling processes may be enabled, one with asampling frequency at an integer sub-harmonic of a desired signal andthe other at the same sampling frequency but with an added time delay,defined by the frequency difference between the desired signal and thelocation of a blocker signal, such that the blocker signal may besubtracted from the desired signal.

FIG. 3B is a block diagram of an exemplary microstrip bandpass filter,in accordance with an embodiment of the invention. Referring to FIG. 3C,there is shown a microstrip bandpass filter 350 comprising threeresonator sections 340, 360 and 380, and input coupler 313 and an outputcoupler 315. Each resonator section 340, 360 and 380 may comprise apattern of signal conductive line 303. In addition, there is shownprogrammable impedances Z₁₂, Z₂₃ and Z₁₃. The pattern of signalconductive line 303 is an exemplary embodiment. The invention is notlimited to this type of structure, as any number of patterns may beutilized to create a bandpass filter. Changing the shape may change thefrequency response of the MS-BPF 350. In this manner, the frequencyresponse may be tuned to a particular range with the design of thesignal conductive line 303, and fine tuning may be accomplished byadjusting the programmable impedances Z₁₂, Z₂₃ and Z₁₃.

The signal conductive line 303 may be as described with respect to FIG.3A. The programmable impedances may comprise inductors and/or capacitorsthat may be programmably adjusted by a processor, such as the processor111 e described with respect to FIG. 1, to modify the center frequencyand bandwidth of the MS-BPF 350. The number and location of theimpedances Z₁₂, Z₂₃ and Z₁₃ is not limited to the configuration shown inFIG. 3B. Accordingly, any number of impedances may be used at multiplelocations within the MS-BPF 350.

The input and output couplers 313 and 315 may comprise inductive tapcouplings for communicating signals into and out of the MS-BPF 350,respectively. In another embodiment of the invention, the input andoutput couplers 313 and 315 may comprise series-capacitance couplers.

In operation, an input signal may be communicated to the MS-BPF 350 viathe input coupler 313. The desired frequency of operation may beconfigured by a processor, such as the processor 111 e described withrespect to FIG. 1, by programming the impedances of the programmableimpedances Z₁₂, Z₂₃ and Z₁₃. The filtered output signal may becommunicated from the output coupler 315.

FIG. 3C is a block diagram illustrating a cross-sectional view of acoplanar waveguide bandpass filter, in accordance with an embodiment ofthe invention. Referring to FIG. 3C, there is shown a coplanar waveguidebandpass filter (CPW-BPF) 300. The CPW-BPF 300 may comprise apassivation layer 301, a signal conductive line 303A, a groundconductive line 303B, an oxide layer 307 and a substrate 309.

The passivation layer 301 may comprise an oxide, nitride or otherinsulating layer that may provide electrical isolation between theconductive lines 303A and 303B and other circuitry on the substrate 309.The passivation layer may provide protection from environmental factorsfor the underlying layers of the CPW-BPF 300. In addition, thepassivation layer 301 may be selected based on its dielectric constantand its effect on the electric field that may be present betweenconductive lines.

The signal and ground conductive lines 303A and 303B may comprise metaltraces embedded in the oxide layer 307. In another embodiment of theinvention, the conductive lines may comprise polysilicon or otherconductive material. The separation and the voltage potential betweenthe signal conductive line 303A and the ground conductive line 303B, aswell as the dielectric constant of the oxide 307 may determine theelectric field generated therein.

The oxide layer 307 may comprise SiO₂ or other oxide material that mayprovide a high resistance insulating layer between the signal conductiveline 303A and the ground conductive line 303B. In addition, the oxidelayer 307 may provide a high resistance insulating layer between thesubstrate 309 and the conductive lines 303A and 303B.

The substrate 309 may comprise a semiconductor or insulator materialthat may provide mechanical support for the CPW-BPF 300 and otherdevices that may be integrated. The substrate 309 may comprise Si, GaAs,sapphire, InP, GaO, ZnO, CdTe, CdZnTe and/or Al₂O₃, for example, or anyother substrate material that may be suitable for integrating coplanarwaveguide structures.

In operation, an AC signal may be applied across the signal conductiveline 303A and the ground conductive line 303B. The spacing between theconductive lines as well as the pattern of the conductive lines maygenerate an inductance and a capacitance that may be utilized forfiltering purposes, specifically bandpass filtering, in the presentinvention. In addition, programmable impedances, which may be configuredby a processor, such as the processor 111 e described with respect toFIG. 1, may be coupled across coplanar waveguide devices in the CPW-BPF300 to tune the center frequency and bandwidth, and will be describedfurther with respect to FIG. 3D.

The CPW-BPF 300 may enable the undersampling of received signals at amuch lower sampling frequency than without filtering. Two undersamplingprocesses may be enabled, both at the same frequency but one with a timedelay, defined by the frequency difference between the desired signaland the location of a blocker signal, such that the blocker signal maybe subtracted from the desired signal.

FIG. 3D is a block diagram of an exemplary coplanar waveguide bandpassfilter, in accordance with an embodiment of the invention. Referring toFIG. 3D, there is shown a coplanar waveguide bandpass filter 325comprising the signal conductive line 303A and the ground conductiveline 303B embedded within an oxide layer and covered with a passivationlayer as described with respect to FIG. 3C. The signal conductive line303A may be as described with respect to FIG. 3C. The pattern of signalconductive line 303A and the ground conductive line 303B is an exemplaryembodiment. The invention is not limited to this type of structure, asany number of patterns may be utilized to create a bandpass filter.

In operation, an input signal may be communicated to the MS-BPF 350 atthe plus and minus inputs labeled as “In” in FIG. 3D. The desiredfrequency of operation may be configured by the design of the conductivelines 303A and 303B. Changing the shape may change the frequencyresponse of the CPW-BPF 325. In this manner, the frequency response maybe tuned to a particular range with the design of the signal conductiveline 303A and the ground conductive line 303B. Tuning may beaccomplished by adjusting the dimensions of the structure, via switchingsections in and out of the structure, for example. In another embodimentof the invention, tuning may be accomplished by suspending portions ofthe CPW-BPF 325 over the substrate with an air gap. By adjusting thisair gap, which may be configured by a processor, such as the processor111 e described with respect to FIG. 1, via piezoelectric orelectrostatic means, for example, the capacitance of the structure maybe altered, adjusting the filter frequency. The filtered output signalmay be communicated out of the CPW-BPF 325 at the plus and minus outputslabeled as “Out” in FIG. 3D.

FIG. 4 is a block diagram illustrating a desired RF signal and a blockersignal, in accordance with an embodiment of the invention. Referring toFIG. 4, there is shown an RF signal versus frequency plot. The desiredchannel 401 may comprise the signal at the desired frequency, and theblocker signal 403 may comprise an undesirable interfering channel. Thedifference in frequency between the two signals, Δf, may be utilized bythe blocker signal filtering system, described with respect to FIG. 2,to configure the adjustable time delay, T_(d).

The center frequency and bandwidth of the filter may be adjustable toallow for channel selection. In addition, the bandwidth may be adjustedto match that of the desired channel. Applying the received RF signal toa bandpass filter centered at the desired channel frequency may resultin the unwanted channels being filtered out. The filtered signal maythen be undersampled, by the S/H circuits 205A and 205B, for example.The desired baseband signal may be generated by subtracting the twoundersampled signals.

FIG. 5 is a flow diagram illustrating a dual-undersampling blockersignal cancellation process, in accordance with an embodiment of theinvention. Referring to FIG. 5, after start step 501, in step 503, theRF signal may be received and the center frequency and bandwidth of themicrostrip or coplanar waveguide bandpass filter may be set. In step505, the signal may be filtered by the microstrip or coplanar waveguidebandpass filter, such that unwanted channels may be removed. In step507, the filtered RF signal may be undersampled by two S/H circuits,both at a sampling frequency of f_(s), but one with a time delay,corresponding to the frequency difference between the desired signal anda blocker signal. In step 509, the signal generated by subsampling atf_(s) with the time delay T_(d), may be subtracted from the signalgenerated by the S/H circuit 205A, resulting in the desired basebandsignal without the blocker signal, followed by end step 511.

In an embodiment of the invention, a method and system are disclosed forband-limiting a received wireless signal utilizing a programmablebandpass filter 325/350, generating a first signal 221 by undersamplingthe signal utilizing a clock signal 215 and generating a second signal219 by undersampling the signal utilizing the clock signal 215 with anadded time delay, T_(d), incorporated by the processor 111 e. The secondsignal 219 may be subtracted from the first signal 221. The programmablebandpass filter 325/350 may comprise a microstrip 350 and/or a coplanarwaveguide 325 bandpass filter. The added time delay, T_(d), may bevariable, and may be defined as an inverse of a difference between thedesired channel and a blocker signal, Δf. The bandwidth of theprogrammable bandpass filter 325/350 may be centered at the desiredchannel. The clock signal 213 may be generated at a frequency, f_(CLK),which may be an integer sub-harmonic of the desired channel, and may begreater than twice a bandwidth of the programmable bandpass filter325/350. The time delay, T_(d), may be controlled by a programmabledelay circuit 213, which may comprise CMOS inverters.

Certain embodiments of the invention may comprise a machine-readablestorage having stored thereon, a computer program having at least onecode section for utilizing undersampling to remove in-band blockersignals, the at least one code section being executable by a machine forcausing the machine to perform one or more of the steps describedherein.

Accordingly, aspects of the invention may be realized in hardware,software, firmware or a combination thereof. The invention may berealized in a centralized fashion in at least one computer system or ina distributed fashion where different elements are spread across severalinterconnected computer systems. Any kind of computer system or otherapparatus adapted for carrying out the methods described herein issuited. A typical combination of hardware, software and firmware may bea general-purpose computer system with a computer program that, whenbeing loaded and executed, controls the computer system such that itcarries out the methods described herein.

One embodiment of the present invention may be implemented as a boardlevel product, as a single chip, application specific integrated circuit(ASIC), or with varying levels integrated on a single chip with otherportions of the system as separate components. The degree of integrationof the system will primarily be determined by speed and costconsiderations. Because of the sophisticated nature of modernprocessors, it is possible to utilize a commercially availableprocessor, which may be implemented external to an ASIC implementationof the present system. Alternatively, if the processor is available asan ASIC core or logic block, then the commercially available processormay be implemented as part of an ASIC device with various functionsimplemented as firmware.

The present invention may also be embedded in a computer programproduct, which comprises all the features enabling the implementation ofthe methods described herein, and which when loaded in a computer systemis able to carry out these methods. Computer program in the presentcontext may mean, for example, any expression, in any language, code ornotation, of a set of instructions intended to cause a system having aninformation processing capability to perform a particular functioneither directly or after either or both of the following: a) conversionto another language, code or notation; b) reproduction in a differentmaterial form. However, other meanings of computer program within theunderstanding of those skilled in the art are also contemplated by thepresent invention.

While the invention has been described with reference to certainembodiments, it will be understood by those skilled in the art thatvarious changes may be made and equivalents may be substituted withoutdeparting from the scope of the present invention. In addition, manymodifications may be made to adapt a particular situation or material tothe teachings of the present invention without departing from its scope.Therefore, it is intended that the present invention not be limited tothe particular embodiments disclosed, but that the present inventionwill include all embodiments falling within the scope of the appendedclaims.

1. A method for wireless communication, the method comprising: in awireless receiver, band-limiting a received wireless signal utilizing aprogrammable bandpass filter; generating a first signal by undersamplingsaid band-limited received wireless signal utilizing a clock signal;generating a second signal by undersampling said band-limited receivedwireless signal utilizing a delayed version of said clock signal; andsubtracting said second signal from said first signal.
 2. The methodaccording to claim 1, wherein said programmable bandpass filtercomprises a microstrip bandpass filter.
 3. The method according to claim1, wherein said programmable bandpass filter comprises a coplanarwaveguide bandpass filter.
 4. The method according to claim 1,comprising varying said delayed version of said clock signal.
 5. Themethod according to claim 1, comprising centering said bandwidth of saidprogrammable bandpass filter at a desired channel of said receivedwireless signal.
 6. The method according to claim 5, comprisingconfiguring a delay of said delayed version of said clock signal as aninverse of a frequency difference between said desired channel and ablocker signal.
 7. The method according to claim 5, comprisinggenerating said clock signal at a frequency which is an integersub-harmonic of said desired channel.
 8. The method according to claim7, wherein said clock signal frequency is greater than twice a bandwidthof said programmable bandpass filter.
 9. The method according to claim1, comprising generating said delayed version of said clock signalutilizing a programmable delay circuit.
 10. The method according toclaim 9, wherein said programmable delay circuit comprises CMOSinverters.
 11. A system for wireless communication, the systemcomprising: one or more circuits in a wireless receiver that enableband-limiting a received wireless signal utilizing a programmablebandpass filter; said one or more circuits generate a first signal byundersampling said band-limited received wireless signal utilizing aclock signal; said one or more circuits generate a second signal byundersampling said band-limited received wireless signal utilizing saidclock signal with an added time delay; and said one or more circuitssubtract said second signal from said first signal.
 12. The systemaccording to claim 11, wherein said programmable bandpass filtercomprises a microstrip bandpass filter.
 13. The system according toclaim 11, wherein said programmable bandpass filter comprises a coplanarwaveguide bandpass filter.
 14. The system according to claim 11, whereinsaid one or more circuits varies said delayed version of said clocksignal.
 15. The system according to claim 11, wherein said one or morecircuits centers said bandwidth of said programmable bandpass filter ata desired channel of said received wireless signal.
 16. The systemaccording to claim 15, wherein said one or more circuits enableconfiguration of a delay of said delayed version of said clock signal asan inverse of a frequency difference between said desired channel and ablocker signal.
 17. The system according to claim 15, wherein said oneor more circuits enable generation of said clock signal at a frequencywhich is an integer sub-harmonic of said desired channel.
 18. The systemaccording to claim 17, wherein said clock signal frequency is greaterthan twice a bandwidth of said programmable bandpass filter.
 19. Thesystem according to claim 11 wherein said one or more circuits enablegeneration of said delayed version of said clock signal utilizing aprogrammable delay circuit.
 20. The system according to claim 20,wherein said programmable delay circuit comprises CMOS inverters.